Furnace



June 16, 1925. 1,542,552

' C. E. HAWKE ET AL FURNACE Filed Feb. 16, 1924 8 Sheets-Sheet l INVENTORSY c. E. HAWKE ET AL June 16, 1925.

- FURNACE File d Feb, 16, 1924 8 Sheets-Sheet 2 Jun le, 192s.

h I I h 13542552 C. E. HAWKE ET AL FURNACE Fi led Feb. ;e, 1924 8 Sheets-Sheet 5 INVENTQR s June .1 1925.

C. E. HAWKE ET AL FURNACE 8 shee tsesheet 5 Filed Feb. 16, 1924 INVENTORS June '16, 1925. 1,542552 C. E. HAWKE ET AL FURNAC E Filed Feb. 1 6 1924 8 Sheets-Sheet 6 June 16, 1925.

C. E. HAWKE ET AL FURNACE Filed Feb. 16, 1924 8 Sheets-Sheet 7 lllizlll Patented June 16,

. UNITED STATES PATENT OFFICE.

CLARENCE E. HAWK'E AND BOYIJM. JOHNSON, OF METUCHEN, NEW JERSEY, AS-

SIGNORS TO THE GARBORUNDUM COMPANY, OF NIAGARA FALLS, NEW YORK, A

CORPORATION OF PENNSYLVANIA summon Application filed February 16, 1924. Serial No. 693,232.

To all whom a may concern:

.Be it known that we, CLARENCE E. HAWKE and Born M.. JOHNSON, citizens of the United States, residing at Metuchen, in the county of Middlesex and State of New Jersey, have invented a new and useful Improvemen't'in Furnaces, of which 'the following is a full, clear, and exact description.

The present invention relates to furnaces or ovens of the indirectly heated type, and more particularlyto furnaces or ovensof this type which are employed for the enameling of iron. and steel and for the heat treatment of'ceramic Wareand similarar: ticles. I

The general purpose of the invention'is to provide a furnace construction in which carbide.

i the energy derived from the combustion'of the fuel may be utilized to the maximum. ex

line II-II of Figure 3; v

' tent and in whichthe refractories are not subjected. to excessive heat conditions or temperature changes. To this end we provide' a, furnace construction embodying a main heating chamber and a pre-heating chamber and'employ silicon carbide radiating combustion chambers to heat, partially by direct and partially by indirect radiation, the ware in the main heating chamber and utilize the waste gases fromsaid combustion chambers to heat the pre-heating chamberand the floor ofthe main heating chamber. The nature of the invention will-be better understood by reference to the accompany? ing drawings, inwhich we have illustrated a preferred embodiment thereof, it being understood that changes may be madein the construction shown without departing from the spirit of the invention or scopeof the appended claims.

In the drawings: Figure 1 is a front elevation of the furnace; I

-' Figure 2 is a transverse sectional view on Figure 3 is a'sectional plan view on line III-III of Figure 2;

Figure 4 is a sectional plan view on line IV-IV of Figure 2; i

Figure 5 is a longitudinal sectional view on .line V-V of Figure 2'; t I Figure ,6'is'a lon 'tudinal sectional view on line VI-VI of igure 2;

In the illustrative embodiment of the invve ntion, the furnace comprises a main'heat-- ingchamberQ and a pr'e-heating chamberv 3 constructed of fire brick in the usual manner. Within the main heating chamber adjacent the opposite sides thereof are airranged two radiating combustion chambers 4, the walls of which are formed of silicon Each combustion chamber is divided into an upper half and a lower half byia horizontal partition wall extending from the front end ofthe chamber nearly to .the rear end thereof. The upper half of each chamber hasa burner opening 6 in the front. end thereof into which projects an oil burner 7 supplied with oil through a pipe 8 and with primary air through a'pipe 9,

secondary air being supplied through a pipe 10, In order to reduce the amount of direct bustion chambers and make the temperature provided intermediate each combustion chamber and the space occupied by the ware, these bafile walls being formed with spacedopenings 12 therein. t V

The floor, 13 of the main heating chamber is constructed of silicon carbide brick and directly beneath this floor is a wide flue 1 1 radiationof'hat to the Ware from the comwith the forward end of which the forward end of the lower half of each combustion chamber communicates, the flue having baffies: 15 therein. The rear end of the flue 14 is connected to a stack 16 through a lower flue 17, while an upper flue 18 connects it with a flue l9 extending beneath the floor of the pro-heating chamber. Another flue 20 extends beneath the floor of the pre-heating' chamber parallel to the flue 19v and communicates with the-stack 16 through aflue 21.

The floorof the pre-heating chamber is provided with openings 22 therein permitting the waste gases flowing through the flue 19 to pass to the flue 20 through the pre-heating .chamber. The lower flue 17 is controlled by a damper23 and the upper flue 18 by a damper 24. y

The dampers 23 and 24 are arranged to be operated simultaneously with the opening and closing of the door 25 of the preheating chamber in such manner that when said door is moved to open position, the damper 24 descends and closes the flue 18, while the damper 23 simultaneously rises and opens the flue 17. This places the flue 14 beneath the main heating chamberin direct communication with the stack when the-door of the pre-heating chamber is open. When the door of the pro-heating chamber is closed, the damper 23 descends and closes the flue 17, while-the damper 24 rises and opens the flue 18, so that when the door of the pre-heating chamber is closed, the flue beneath the main heating chamber is in communication with the stack through ihe pre-heating chamber.

Referring to Figures 8,9 and 10, the door 25. is'counter-balanced by'weights'26 connected to the door by a cable 27 passing over sheaves 28 and 29. The sheave 28 is fixed to a shaft 30 journalled in bearings 31 carriedby vertical members 32 at the rear end-of the furnace. It will be apparent that when'the'door' 25 is raised or lowered, the cable 27 will rotate the sheave 28 and shaft 30.. This shaft drives a parallel shaft 3 through a sprocket chain 34' and sprocket wheels 35 and 36 mounted upon the respective shafts. A rope 37 connects the damper 23 to a drum 38 on the shaft 33, while a similar rope 39 connects the damper 24 to a similar drum 40 on said shaft, the ropes 37 and 39 being wound about said drums in opposite directions. Each of these ropes passes between a pair of guide pulleys 41.

The travel of the combustion gases is as follows: These gases flow back through the upper half of each combustion chamber and return through the lowerhalf and then pass downwardly into the flue 14 beneath the main heating chamber, their travel through this flue being retarded by the baflies 15. If the door of the pre-heating chamber is closed, the waste gases pass through the upper flue 18 into the flue 19 beneath the floor of the pre-heating chamber and then pass through the openings 22 above said flue into the pre-heatin chamber. After circulating in said cham er, the gasespass into the flue 20 beneath the floor of said chamber and then to the stack. On the other hand, if the door of the pre-heating chamber is open, the waste gases pass from the flue 14 directly to the stack through the lower flue 17.

The reason for by-passing the waste ases directly to the stack when the door 0 the pre-heating chamber is open, is to prevent the cutting down of the draft on the combustion chambers which would result when said door is open if no such provision for by-passing the waste gases were made. In

that case the waste gases would not flow into the pre-heating chamber uponopening of the door thereof because the stack pull would be on the pre-heating chamber and cold airwould be pulled to "the stack through the open door of the pre-heating chamber, thereby cutting off the draft from the combustion chambers. vThis would cause a building up of pressure on the combustion I chambers and consequent leakage into the heating chamber. The provision for by-passing the gases in this manner is also advantageous in startin up the furnace in that a proper draft is provided to effect a preliminary heating of the combustion chambers. After the furnace is well up to heat, the by-pass flue 17 may be closed by its damper 23 and the flue 18 s opened.

The great advantage of a'construction as abovedescribed is in its fuel economy. Not only does it utilize silicon carbide combustion chambers in a very eflicient and prac tical manner, so that either by direct or indirect radiation a large percentage of the heat initially generated is radiated to the ware, but in addition to this, the waste gases are further utilized not only for heating the floor of the main' heatin chamber, but for a thermal conductivity about five times that of' the usual fireclay refractories and its emissivity factor is about twice that of such fireclay refractories. Furthermore, by reason of the fact that the floor of the heating chamber, which also forms the top wall of the wasteheat flue beneath said chamber. is constructed of carborundum bricks, a relatively large proportion of the heat of the waste gases passing throughthe waste heat flue is conducted through the floor of the heating chamber to heat the bottom of said chamber. The heat remaining in such gases after passing through the waste heat flue is largely given up in heating the pre-heating chamber and the material placed therein, so that. when the waste gases pass fromsaid chamber to the stack, they retain a relatively small proportion of their original heat.

The furnace has shown in actual operation a fuel consumption far below the best results heretofore attained in silicon carbide muffle furnaces.

' In mufile furnaces in common use of the entails an expensive refractory construction,

because the refractories, in order to conduct heat properly, must necessarily be made in very thin sections. In such constructions, the mufile tile have to be removed at intervals. On the other hand, in a construction from. the other of said flues out of the fursuch as herein disclosed, it is apparent that the furnace structure should last indefinitely as it can be built up of stock sizes in a very solid manner and none of the refractories' are subjected to excessive heat condi-' tions or temperaturechanges.

We claim;

1. A furnace, comprising a heating chamber having. a combustion chamber associated therewith, a pre-heating. chamber, a

pair of flues beneath the floor of' said pre:

heating chamber and each having its top wall formed thereby, said top walls having openings therein establishing communication between said flues and pre-heating chamber, and Jneans for conducting the waste gases from said combustion chamber to one of said flues and for conducting them nace, substantially as described.

2. A furnace, comprising a heating chamber, a combustion chamber having a silicon carbide partitioning wall between it and the heating chamber, a waste heat flue beneath the floor of said heatingcham'ber and having its top wall formed thereby, said top wall being constructed of silicon carbide, a pre-heating chamber, and a flue beneath the floor of said pre-heating chamber and ada ted'to receive the waste gases from the ue beneath the heating chamber, the top wall of the flue beneath the pre-heating chamber being formed by the floor of said chamber, substantially as described.

. 3. A furnace, comprising a heating chamber having a combustion chamber associated therewith, a pre-heating chamber having a door, and means acting automatically to admit the waste gases from the combustion chamber tothe re-heating chamber when the door is closed and to exclude such gases therefrom when the door is opened, substantially as described.

4. A furnace, comprising a heating chamber having a combustion chamber associated therewith, a pre-heating chamber having a door, a stack, a flue for conductin the waste gases from said combustion cham er directly to said stack, a second flue for conducting suchgases into said pre-heating chamber, a damper for contr'olhng each of said flues, and damper-operating means acting to'automatically close the first flue and open the second when the'door'is closed and to open the first flue and close the second when the door is opened, substantially as described.

In: testimony whereof we have hereunto set our hands.

. CLARENCE E. HAWKE.

BOYD M. JOHNSON. 

